Integral chip lid and heat sink

ABSTRACT

An integrally formed chip lid and heat sink of the present invention comprises a chip lid portion, and a heat sink portion formed from said chip lid. The integrally formed chip lid portion and heat sink portion are manufactured as a single part, such that there is no interface between the chip lid portion and the heat sink portion.

FIELD OF THE INVENTION

Embodiments of the present invention relate to microelectronic fabrication, and more particularly to packaging integrated circuits.

BACKGROUND OF THE INVENTION

Referring to FIG. 1, an exemplary thermal stack-up of a microelectronic circuit, according to the conventional art, is shown. As depicted in FIG. 1, the thermal stack-up of the microelectronic circuit comprises a die pad 110, a die (e.g., integrated circuit) 120, a chip lid 130, and a heat sink 140 or other thermally dissipative device. The chip lid 130 is disposed on top of the die 120. The chip lid 130 is adapted to provide physical and environmental protection for the die. The chip lid 130 is also adapted to provide a good thermal path away from the hot die 120. The heat sink 140 is disposed on top of the chip lid 130. The heat sink 140 is adapted to dissipate heat generated by the die 120.

The materials used in the chip lid 130 and heat sink 140 preferably have a low thermal resistance, for use in high thermally conductive applications. However, each interface between such parts adds to the thermal resistance, as a result of imperfect surfaces, trapped air pockets, etc. Accordingly, the interface between the chip lid 130 and heat sink 140 adds additional thermal resistance. The ability of the heat sink 140 to dissipate heat from the die 120 is directly related to the planarity of the thermal interface between the chip lid 130 and the heat sink 140. However, the planarity of the chip lid surface and the heat sink surface, which are to be in contact with each other, is difficult to maintain in production. Variations in the planarity result in yield losses and the like. Furthermore, maintaining tight tolerance on the planarity between the chip lid 130 and the heat sink 140 requires specialized manufacturing processes. The specialized manufacturing processes result in higher unit costs and the like.

One solution according to the conventional art is to increase the size of the heat sink 140 and/or use more expensive heat sink material. Such heat sinks 140 having increased size and/or better quality heat sinking materials are used to partially make up for the poor thermal interface between the chip lid 130 and the heat sink 140. However, increasing the size of the heat sink 140 or fabricating it from better quality heat sinking materials deleteriously increases the cost of the device and our exceeds dimensional restricts in desired applications.

Another solution according to the conventional art is to add a thermal interface material (e.g., thermal epoxy, thermal grease, thermal foil, or the like) 150 to make up for deviations in the planarity of the chip lid 130 and/or heat sink 140. However, such solutions depend greatly on assembly tolerances, require extra assembly steps, require additional parts, and/or have limited effectiveness. In addition, the solution suffers from increased manufacturing costs, and yield losses in manufacturing and in the field due to incorrect manufacture and assembly.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide an integrally formed chip lid and heat sink. In one embodiment, the integrally formed chip lid and heat sink comprises a chip lid portion, and a heat sink portion formed from said chip lid. Accordingly, embodiments of the present invention are advantageous in that the thermal interface between the chip lid and the heat sink is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

FIG. 1 shows an exemplary thermal stack-up of a microelectronic circuit, according to the conventional art.

FIG. 2 shows a sectional perspective view of an exemplary integrally formed chip lid and heat sink, in accordance with one embodiment of the present invention.

FIG. 3 shows a sectional view of an exemplary integrally formed chip lid and heat sink, in accordance with one embodiment of the present invention.

FIG. 4 shows a plurality of views of an exemplary integrally formed chip lid and heat sink, in accordance with another embodiment of the present invention.

FIG. 5 shows a flow diagram of a method of fabricating an integral chip lid and heat sink, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with these embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it is understood that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.

Referring now to FIG. 2, a sectional perspective view of an exemplary integrally formed chip lid and heat sink, in accordance with one embodiment of the present invention, is shown. As depicted in FIG. 2, the integrally formed chip lid and heat sink comprises a chip lid portion 210 and a heat sink portion 220 formed from the chip lid. A die 240, a plurality of contacts 295 and die pad 296 are also shown for illustrative purposes.

In one embodiment, the chip lid portion 210 may comprise a integrated circuit package such as a TO package, a dual inline package (DIP), a single inline package (SIP), a zigzag inline package (ZIP), a pin-grid array (PGA), a leadless chip carrier (LCC), a surface mount package, a ball grid array (BGA) (as illustrated in FIG. 2), a Chip scale package (CSP), or the like.

In one embodiment, the heat sink portion 220 may comprise a plurality of stacked fins 270 (as illustrated in FIG. 2), folded fins, a boxed fin, pin field fins, or the like. In another embodiment, the heat sink portion 220 may comprise one or more heat sink fin receptacles. The heat sink fin receptacles may comprise one or more trenches, grooves, footings, braces or the like.

In one embodiment, the chip lid portion 210 and the heat sink portion 220 may be comprised of a high thermally conductive material such as ceramic, metal (e.g., copper), ceramic infused with metal (e.g., alumina), and or the like. However, it is appreciated that embodiments of the present invention may also utilize low thermally conductive materials such as plastic, epoxy and the like.

In one embodiment, the integrally formed chip lid and heat sink may optionally comprise a die receptacle 230 integrally formed in the chip lid portion 210. The die receptacle 230 provides a cavity for receiving the die 240. In one embodiment, the chip lid portion 210 may also comprise a pedestal 250 for providing a thermal contact from the die 240 to the integrally formed chip lid and heat sink. In one embodiment, thermal grease, epoxy or the like 260 may be utilized to increase the thermal coupling between the die 240 and the pedestal 250. However, it should be appreciated that the chip lid portion 210 may be placed in direct contact with the die 240 (e.g., without the use of a pedestal, thermal grease and/or the like).

In one embodiment, the die receptacle 230 is orientated in the chip lid portion 210 such that one or more fins 270 of the heat sink portion 220 are orientated parallel to an air flow 280 about the heat sink portion 220. In one embodiment the die receptacle is formed contemporaneously with formation of the chip lid portion and the heat sink portion. In another embodiment, the die receptacle is formed subsequent to formation of the chip lid portion and the heat sink portion (e.g., upon determination of air flow in a particular application).

In one embodiment, the integrally formed chip lid and heat sink may optionally comprise a vapor chamber, heat pipe or the like 290 formed in the heat sink portion 220. In one embodiment, the vapor chamber contains liquid water at a low-pressure.

Referring now to FIG. 3, a sectional view of an exemplary integrally formed chip lid and heat sink, in accordance with one embodiment of the present invention, is shown. As depicted in FIG. 3, the integrally formed chip lid and heat comprises a chip lid portion 310, and a heat sink portion 320 formed from the chip lid 310. A die 350, a plurality of contacts 395, a printed circuit board, flexible substrate or the like 396, and a sealing/attaching means 397 are also shown for illustrative purposes.

In one embodiment, the chip lid portion 310 may comprise a integrated circuit package such as a TO package, a dual inline package (DIP), a single inline package (SIP), a zigzag inline package (ZIP), a pin-grid array (PGA), a leadless chip carrier (LCC), a surface mount package, a ball grid array (BGA), a Chip scale package (CSP) (as illustrated in FIG. 3), or the like.

In one embodiment, the heat sink portion 320 may comprise one or more heat sink fin receptacles 330 (as illustrated in FIG. 3). The heat sink fin receptacles may comprise one or more trenches, grooves, footings, braces or the like. In another embodiment, the heat sink portion 320 may comprise a plurality of stacked fins, folded fins, a boxed fin, pin field fins, or the like.

In one embodiment, the chip lid portion 310 and the heat sink portion 320 may be comprised of a high thermally conductive material such as ceramic, metal (e.g., copper), ceramic infused with metal (e.g., alumina), and or the like. However, it is appreciated that embodiments of the present invention may also utilize low thermally conductive materials such as plastic, epoxy and the like.

In one embodiment, the integrally formed chip lid and heat sink may optionally comprise a die receptacle 340 integrally formed in the chip lid portion 310. The die receptacle 340 provides a cavity for receiving an integrated circuit die 350. In one embodiment, the chip lid portion 310 may also comprise a pedestal for providing a thermal contact from the die 350 to the integrally formed chip lid and heat sink. In one embodiment, a thermal grease, epoxy or the like 360 may be utilized to increase the thermal coupling between the die 350 and the chip lid portion 310. However, it should be appreciated that the chip lid portion 310 may be placed in direct contact with the die 350 (e.g., without the use of a pedestal, thermal grease and/or the like).

In one embodiment, the die receptacle 340 is orientated in the chip lid portion 310 such that one or more heat sink fin receptacles 330 and/or heat sink fins are orientated parallel to an airflow about the heat sink portion 320. In one embodiment the die receptacle 340 is formed contemporaneously with formation of the chip lid portion 310 and the heat sink portion 320. In another embodiment, the die receptacle 340 is formed subsequent to formation of the chip lid portion 310 and the heat sink portion 320 (e.g., upon determination of air flow in a particular application).

In one embodiment, the integrally formed chip lid and heat sink may optionally comprise a vapor chamber, heat pipe or the like formed in the heat sink portion 320. In one embodiment, the vapor chamber contains liquid water at a low-pressure.

Referring now to FIG. 4, a plurality of views of an exemplary integrally formed chip lid and heat sink, in accordance with another embodiment of the present invention, is shown. As depicted in the top, side and front views, the integrally formed chip lid and heat sink, in accordance with one embodiment, comprises a plurality of heat sink fin receptacles 410. In one implementation, the plurality of heat sink fin receptacles may be arranged as a plurality of parallel elongated trenches, grooves, footings, braces and/or the like. In another implementation, the plurality of heat sink fin receptacles may be arranged as a plurality of parallel and perpendicular elongated grooves (as illustrated in FIG. 4). The grid of parallel and perpendicular fin receptacles allow fins to be attached in either or both directions, depending upon the requirements of a particular application.

A plurality of heat sink fins may be attached to the heat sink receptacles. In another embodiment, the integrally formed chip lid and heat sink comprises a plurality of heat sink fins. The heat sink fins may comprise a plurality of stacked fins, folded fins, a boxed fin, pin field fins, or the like.

As depicted in the bottom view, the integrally formed chip lid and heat sink further comprises a die receptacle 420. The die receptacle 420 provides a cavity for receiving an integrated circuit die. Optionally, the integrally formed chip lid and heat sink may further comprise a pedestal 430. The pedestal 430 provides a thermal contact from the die to the integrally formed chip lid and heat sink.

In one embodiment, the integrally formed chip lid and heat sink may comprise a integrated circuit package such as a TO package, a dual inline package (DIP), a single inline package (SIP), a zigzag inline package (ZIP), a pin-grid array (PGA), a leadless chip carrier (LCC), a surface mount package, a ball grid array (BGA), a Chip scale package (CSP), or the like.

In one embodiment, the integrally formed chip lid and the heat sink may be comprised of a high thermally conductive material such as ceramic, metal (e.g., copper), ceramic infused with metal (e.g., alumina), and or the like. However, it is appreciated that embodiments of the present invention may also utilize low thermally conductive materials such as plastic, epoxy and the like.

In one embodiment, the integrally formed chip lid and heat sink may optionally comprise a vapor chamber. In one embodiment, the vapor chamber contains liquid water at a low-pressure.

Referring now to FIG. 5, a flow diagram of a method of fabricating an integral chip lid and heat sink, in accordance with one embodiment of the present invention, is shown. As depicted in FIG. 5, the method comprises forming a chip lid portion, at 510, and forming a heat sink portion integrally with the chip lid portion, at 520. The chip lid portion and heat sink portion may be integrally formed by a process such as molding, casting, machining, forging and/or the like. In one implementation the heat sink portion comprises one or more heat sink fins such as a plurality of stacked fins, folded fins, a box fin, pin field fins, or the like.

Additionally, the method may further comprise forming a die receptacle in the chip lid portion, at 530. The method may also further comprise forming a pedestal in the chip lid portion.

Additionally, the method may further comprise forming a vapor chamber, heat pipe or the like in the heat sink portion, at 540. In one implementation, the vapor chamber comprises a vessel filed with water at a low pressure.

Additionally, the method may further comprises forming one or more heat sink receptacles such as one or more trenches, grooves, footings, braces or the like, at 550, instead of forming one or more heat sink fins. Additionally, the method may further comprise attaching one or more heat sink fins to the heat sink portion, at 560. In one embodiment, one or more heat sink fins, such as stacked fins, folded fins, boxed fins, pin field fins, or the like are attached to the heat sink portion at one or more of the trenches, grooves, footings, braces or the like. In one implementation, fins such as stacked fins or folded fins are attached to the heat sink portion such that they are orientated parallel to a flow of air for a particular application. In another implementation, fins such as boxed fins or pin filed fins, which are airflow orientation independent, are attached to the heat sink portion.

Additionally, the method may further comprise attaching the integral chip lid and heat sink to a die, at 570. The integral chip lid and heat sink may be attached utilizing an epoxy, clamp or the like.

In an exemplary implementation, a chip lid portion and heat sink portion are integrally formed utilizing a forging process, at 510 and 520. The chip lid portion and heat sink portion may be formed from a metal. A die receptacle is also contemporaneously formed during the forging process, at 530. A plurality of heat sink receptacles are also contemporaneously formed during the forging process, at 550. The heat sink receptacles may be formed as a plurality of parallel and perpendicular grooves.

Upon determination of the particular application in which the integral chip lid and heat sink will be utilized, a plurality of stacked heat sink fins are attached to the heat sink receptacles, at 560. The plurality of stacked heat sink fins are attached to the heat sink receptacles such that they are parallel to a flow of air in the particular application.

In another exemplary implementation, a chip lid portion and heat sink portion are integrally formed utilizing a molding process, at 510 and 520. The chip lid portion and heat sink portion may be formed from a ceramic infused with a metal. The heat sink portion comprises a plurality of stacked heat sink fins. A vapor chamber is also contemporaneously formed, at 540 during the molding process.

Upon determination of the particular application in which the integral chip lid and heat sink will be utilized, a die receptacle is formed utilizing a machining process, at 530. The die receptacle is formed in the chip lid portion such that the heat sink fins are parallel to a flow of air in the particular application.

Embodiments of the present invention provide an integrally formed chip lid and heat sink. The integral chip lid portion and heat sink portion are manufactured as a single part, such that there is no interface between the chip lid portion and the heat sink portion. Accordingly, embodiments of the present invention are advantageous in that the thermal interface between the chip lid and the heat sink is eliminated. Embodiments of the present invention are also advantageous in that fewer parts are required, thus potentially reducing device costs. Furthermore, embodiments of the present invention are also advantageous in that the more efficient thermal conduction achieved can allow for smaller/shorter heat sinks. Such solutions provide equivalent cooling where space is a premium. In addition, equivalent cooling can also be achieved in lower airflow environments or without the need for expensive exotic heat sinks, fans, and/or the like.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. An integrally formed chip lid and heat sink comprising: a chip lid portion; and a heat sink portion formed from said chip lid.
 2. The integrally formed chip lid and heat sink according to claim 1, further comprising a die receptacle integrally formed in said chip lid portion.
 3. The integrally formed chip lid and heat sink according to claim 2, wherein said die receptacle is orientated in said chip lid portion such that said heat sink portion is orientated parallel to an airflow about said heat sink portion.
 4. The integrally formed chip lid and heat sink according to claim 1, further comprising a vapor chamber formed in said heat sink portion.
 5. The integrally formed chip lid and heat sink according to claim 1, wherein said chip lid portion and said heat sink portion are formed from a thermally conductive material selected from the group consisting of a metal, a ceramic, a ceramic infused with metal, a plastic and an epoxy.
 6. The integrally formed chip lid and heat sink according to claim 1, wherein said heat sink portion comprises a fin selected from a group consisting of a folded fin, a stacked fin, a boxed fin and a pin field fin.
 7. The integrally formed chip lid and heat sink according to claim 1, further comprising a pedestal formed in said chip lid portion.
 8. An integrally formed chip lid and heat sink comprising: a chip lid portion; and a heat sink portion formed from said chip lid, wherein said heat sink portion comprises a heat sink fin receptacle.
 9. The integrally formed chip lid and heat sink according to claim 8, further comprising a heat sink fin coupled to said heat sink fin receptacle.
 10. The integrally formed chip lid and heat sink according to claim 8, wherein said heat sink portion further comprises a vapor chamber.
 11. The integrally formed chip lid and heat sink according to claim 8, further comprising a die receptacle integrally formed in said chip lid portion.
 12. The integrally formed chip lid and heat sink according to claim 11, wherein said die receptacle is orientated in said chip lid portion such that said heat sink portion is orientated parallel to an airflow about said heat sink portion.
 13. A method of fabricating an integral chip lid and heat sink comprising: forming a chip lid portion; and forming a heat sink portion integrally with said chip lid.
 14. The method according to claim 13, wherein forming said chip lid portion comprises a process selected from the group consisting of molding, casting, machining and forging.
 15. The method according to claim 13, wherein forming said heat sink portion comprises a process selected from the group consisting of molding, casting, machining and forging.
 16. The method according to claim 13, further comprising forming a vapor chamber in said heat sink portion.
 17. The method according to claim 13, further comprising forming a heat sink fin receptacle in said heat sink portion.
 18. The method according to claim 17, further comprising attaching a heat sink fin to said heat sink fin receptacle.
 19. The method according to claim 13, further comprising forming a plurality of heat sink fin receptacles in said heat sink portion.
 20. The method according to claim 19, further comprising attaching a plurality of heat sink fins to said plurality of heat sink fin receptacles, wherein said plurality of heat sink fins are selected from a group consisting of a stacked fin, a folded fin, a boxed fin and a pin field fin. 